Seals of the type involved here are used in hydraulic valve devices comprising a housing having a valve body movable in a bore therein. A plurality of apertures opening into the bore are provided in the wall of the housing, said apertures being adapted to communicate with a conduit provided in the valve body and opening into the peripheral surface thereof, dependent on the position of the valve body. An annular sealing means is provided in the counter-bored conduit mouth, and the sealing means is in engagement with the bore wall.
Such a hydraulic valve device is known from the German Gebrauchsmuster No. 7408649. The application of a sealing means in the transition(s) of the aperture(s) between the housing and the mouth(s) of the conduit in the valve body has the advantage that a relatively large clearance is acceptable between the bore wall and the valve body without this being at the cost of the leak tightness of the valve device, as is the case with other known constructions without such a sealing means. A larger clearance means larger manufacturing tolerances and therefore cheaper manufacture, while the valve body may more easily be actuated with a larger clearance than with a narrow clearance of the valve body in the bore. In the known construction according to the above mentioned Gebrauchsmuster, the sealing means is composed of two parts: an annulus of relatively hard material engaging the bore wall and an annulus of relatively elastic material which in prestressed condition is received in the counter-bore of the conduit mouth in the valve body and pushes the first mentioned annulus outwardly against the bore wall.